Observation of CP violation in two-body B s 0 $$ {B}_{(s)}^0 $$ -meson decays to charged pions and kaons

Abstract

Abstract

The time-dependent CP asymmetries of B0 → π+π− and

B s 0

$$ {B}_s^0 $$ → K+K− decays are measured using a data sample of pp collisions corresponding to an integrated luminosity of 1.9 fb−1, collected with the LHCb detector at a centre-of-mass energy of 13 TeV. The results are

C ππ

= − 0.311 ± 0.045 ± 0.015 ,

S ππ

= − 0.706 ± 0.042 ± 0.013 ,

C KK

= 0.123 ± 0.034 ± 0.015 ,

S KK

= 0.164 ± 0.034 ± 0.014 ,

A KK

Δ Γ

= − 0.83 ± 0.05 ± 0.09 ,

$$ {\displaystyle \begin{array}{c}{C}_{\pi \pi}=-0.311\pm 0.045\pm 0.015,\\ {}{S}_{\pi \pi}=-0.706\pm 0.042\pm 0.013,\\ {}{C}_{KK}=0.123\pm 0.034\pm 0.015,\\ {}{S}_{KK}=0.164\pm 0.034\pm 0.014,\\ {}{\mathcal{A}}_{KK}^{\Delta \varGamma }=-0.83\pm 0.05\pm 0.09,\end{array}} $$

where the first uncertainties are statistical and the second systematic. The same data sample is used to measure the time-integrated CP asymmetries of B0 → K + π− and

B s 0

$$ {B}_s^0 $$ → K−π+ decays and the results are

A CP

B 0

= − 0.0824 ± 0.0033 ± 0.0033 ,

A CP

B s 0

= 0.236 ± 0.013 ± 0.011 .

$$ {\displaystyle \begin{array}{c}{A}_{CP}^{B^0}=-0.0824\pm 0.0033\pm 0.0033,\\ {}{A}_{CP}^{B_s^0}=0.236\pm 0.013\pm 0.011.\end{array}} $$

All results are consistent with earlier measurements. A combination of LHCb measurements provides the first observation of time-dependent CP violation in

B s 0

$$ {B}_s^0 $$ decays.